Senocular.com have posted a new tutorial, the Beginners Guide to Getting Started with AS3 (Without Learning Flex). Surely learning Flex and MXML is an integral part of AS3? Regardless, it’s an interesting article that’s worth a read.
If you’re new to AS3 you should read the Actionscript 2 to Actionscript 3 migration guide and the Flex 2/AS3 language reference.